]>
Commit | Line | Data |
---|---|---|
e814f4b0 | 1 | /* Return a range of open file descriptors. |
dff8da6b | 2 | Copyright (C) 2021-2024 Free Software Foundation, Inc. |
e814f4b0 AZ |
3 | This file is part of the GNU C Library. |
4 | ||
5 | The GNU C Library is free software; you can redistribute it and/or | |
6 | modify it under the terms of the GNU Lesser General Public | |
7 | License as published by the Free Software Foundation; either | |
8 | version 2.1 of the License, or (at your option) any later version. | |
9 | ||
10 | The GNU C Library is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | Lesser General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU Lesser General Public | |
16 | License along with the GNU C Library; if not, see | |
17 | <https://www.gnu.org/licenses/>. */ | |
18 | ||
19 | #include <errno.h> | |
20 | #include <fcntl.h> | |
21 | #include <support/support.h> | |
22 | #include <support/check.h> | |
23 | #include <support/xunistd.h> | |
24 | #include <stdlib.h> | |
25 | #include <sys/resource.h> | |
26 | ||
27 | static void | |
28 | increase_nofile (void) | |
29 | { | |
30 | struct rlimit rl; | |
31 | if (getrlimit (RLIMIT_NOFILE, &rl) == -1) | |
32 | FAIL_EXIT1 ("getrlimit (RLIMIT_NOFILE): %m"); | |
33 | ||
34 | rl.rlim_cur += 128; | |
35 | ||
36 | if (setrlimit (RLIMIT_NOFILE, &rl) == 1) | |
37 | FAIL_EXIT1 ("setrlimit (RLIMIT_NOFILE): %m"); | |
38 | } | |
39 | ||
40 | static int | |
41 | open_dev_null (int flags, mode_t mode) | |
42 | { | |
27b6edbb SP |
43 | int fd = open64 ("/dev/null", flags, mode); |
44 | if (fd >= 0) | |
45 | return fd; | |
e814f4b0 | 46 | |
27b6edbb SP |
47 | if (fd < 0 && errno != EMFILE) |
48 | FAIL_EXIT1 ("open64 (\"/dev/null\", 0x%x, 0%o): %m", flags, mode); | |
e814f4b0 | 49 | |
27b6edbb | 50 | increase_nofile (); |
e814f4b0 | 51 | |
27b6edbb | 52 | return xopen ("/dev/null", flags, mode); |
e814f4b0 AZ |
53 | } |
54 | ||
55 | struct range | |
56 | { | |
57 | int lowfd; | |
58 | size_t len; | |
59 | }; | |
60 | ||
61 | struct range_list | |
62 | { | |
63 | size_t total; | |
64 | size_t used; | |
65 | struct range *ranges; | |
66 | }; | |
67 | ||
68 | static void | |
69 | range_init (struct range_list *r) | |
70 | { | |
71 | r->total = 8; | |
72 | r->used = 0; | |
73 | r->ranges = xmalloc (r->total * sizeof (struct range)); | |
74 | } | |
75 | ||
76 | static void | |
77 | range_add (struct range_list *r, int lowfd, size_t len) | |
78 | { | |
79 | if (r->used == r->total) | |
80 | { | |
81 | r->total *= 2; | |
82 | r->ranges = xrealloc (r->ranges, r->total * sizeof (struct range)); | |
83 | } | |
84 | r->ranges[r->used].lowfd = lowfd; | |
85 | r->ranges[r->used].len = len; | |
86 | r->used++; | |
87 | } | |
88 | ||
89 | static void | |
90 | range_close (struct range_list *r) | |
91 | { | |
92 | for (size_t i = 0; i < r->used; i++) | |
93 | { | |
94 | int minfd = r->ranges[i].lowfd; | |
95 | int maxfd = r->ranges[i].lowfd + r->ranges[i].len; | |
96 | for (int fd = minfd; fd < maxfd; fd++) | |
97 | xclose (fd); | |
98 | } | |
99 | free (r->ranges); | |
100 | } | |
101 | ||
102 | int | |
103 | support_open_dev_null_range (int num, int flags, mode_t mode) | |
104 | { | |
105 | /* We keep track of the ranges that hit an already opened descriptor, so | |
106 | we close them after we get a working range. */ | |
107 | struct range_list rl; | |
108 | range_init (&rl); | |
109 | ||
110 | int lowfd = open_dev_null (flags, mode); | |
111 | int prevfd = lowfd; | |
112 | while (true) | |
113 | { | |
114 | int i = 1; | |
115 | for (; i < num; i++) | |
116 | { | |
117 | int fd = open_dev_null (flags, mode); | |
118 | if (fd != lowfd + i) | |
119 | { | |
120 | range_add (&rl, lowfd, prevfd - lowfd + 1); | |
121 | ||
122 | prevfd = lowfd = fd; | |
123 | break; | |
124 | } | |
125 | prevfd = fd; | |
126 | } | |
127 | if (i == num) | |
128 | break; | |
129 | } | |
130 | ||
131 | range_close (&rl); | |
132 | ||
133 | return lowfd; | |
134 | } |